No problem
The FXD70 and 80 are pretty similar, but the 70 have better bass impact (even though the graph show them as having
8 dB or so less bass) and a slightly fuller more coherent presentation with little less air.
I agree that FXD series lack texture in the bass but it's faster and more solid than FXH which works well with fast well produced music, and that at times you can get a slightly metallic tinge. That slightly steely timbre works great with synth and well produced instrumental music and perhaps not as great with some voices and badly produced hot stuff. The fact that it's not a smoothed over treble adds texture and weight to instruments which is something I preferred to say the soft touch treble of the IE800.
I remembering having the same discussion when the much warmer FXZ100/200 came out and everybody was hyping it as a super upgrade to the FXD series but when listening to them side by side you could tell it was more a sidegrade than upgrade from a technical stand point with the FXD series sounding faster, more coherent and clearer and being better with some music and poorer with other.
Usually I let an earphone go in my burn in apparatus for a 100 hours before initial comments and at times can you see a tightness and reduction in the bass (like the AT CKS70 for example).
As of now I feel it's a great in-ear handicapped by an out of control bass bleeding into the great mids hampering transparency. For badly recorded modern stuff I would recommend FXH over the FXDs.
Listening to my reference badly recorded modern track, From the Bughouse, which is a great track but produced like ****, it's clear the FXH is the winner even though the bass sounds bloated and slow with voices and instruments sounding more fleshed out and smooth.
I listen to the FXD70 at slightly louder than normal listening volumes and with a superdeep fit from a good amp which takes away some of the thinness, but I'm the first to admit they are in need of some EQ to show the full potential of the drivers.